Covid-19 is a new disease caused by infection with the SARS-CoV2 virus, little is known so far about the impact it might have on pregnancy outcomes if a woman gets Covid-19 whilst pregnant. We are proposing to use de-identified electronic primary care records to investigate whether having Covid-19 during pregnancy increases the chances of the pregnancy ending in miscarriage or stillbirth (pregnancy loss).We will use data from the first wave of the Covid-19 pandemic in the UK (01/03/2020 - 10/06/2020). We will look at whether there is any change in risk depending on the severity of the Covid-19 disease or at which stage of pregnancy it is contracted. Furthermore, there is the potential that broader factors associated with the pandemic itself resulted in an increased chance of pregnancy loss for example reduced contact with healthcare providers, we will explore this and any interaction it may have with the relationship between Covid-19 and pregnancy loss. Finally, ascertaining when a woman is pregnant in electronic primary care records can be challenging. There may be a chance that pregnancy loss is less likely to be recorded completely than live births. Building on previous research we have done we will use this study to examine whether adjusting the way we define pregnancy in the data changes the results of our analysis. We hope to provide valuable insight into the potential risks of having Covid-19 whilst pregnant.
Since the emergence of the SARS-COv2 virus and its associated illness Covid-19, a number of studies and case reports have hypothesised a potential increased risk of pregnancy loss (miscarriage or stillbirth) associated with Covid-19 whilst pregnant. We propose to examine this potential association with a large-scale observational cohort study in CPRD Aurum.
We will use the CPRD Aurum Pregnancy Register to select women whose pregnancy began between 01/03/2020 and the 10/06/2020 with no record of Covid-19 prior to their pregnancy. We will match women with a record of Covid-19 during pregnancy with controls who are at the same gestational and maternal age. Using a Cox regression model we will estimate the hazard ratio for the risk of pregnancy loss between those who had Covid-19 whilst pregnant and those who did not. We will also select a historical comparison cohort of woman who were pregnant in 2018 in order to examine whether factors associated with the pandemic itself, such as reduced healthcare contacts, had an impact on the risk of pregnancy loss.
Whilst CPRD pregnancy registers are extremely useful the nature of the data means they contain uncertain pregnancy episodes. Our previous research examined reasons these episodes might exist and the potential impact of their inclusion or exclusion from studies. We will use this study to apply recommendations from our research on the optimal way to handle uncertain episodes by changing the criteria we use to select pregnancies and examining any impact this has on the results. We will use linked secondary care to obtain additional pregnancy information missing from the primary care records.
This study will not only provide valuable insight into the relationship between Covid-19 and pregnancy loss but will also act as proof of concept study for our recommended methodologies when using electronic health records to study pregnancy.
Miscarriage and Stillbirth.
Jennifer Campbell - Chief Investigator - CPRD
Jennifer Campbell - Corresponding Applicant - CPRD
Clara Calvert - Collaborator - University of Edinburgh
Krishnan Bhaskaran - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Rachael Williams - Collaborator - CPRD
CPRD Mother-Baby Link;HES Admitted Patient Care;HES Diagnostic Imaging Dataset;HES Outpatient;Patient Level Index of Multiple Deprivation Domains;Pregnancy Register;SGSS (Second Generation Surveillance System);COVID-19 Linkages